1. Field of the Invention:
This invention relates to a process for the manufacture of surface-active saturated sulfophosphoric acid-(partial)-alkyl esters and their alkali metal, alkaline earth, ammonium and/or amine salts by the sulfonation of saturated phosphoric acid-(partial)-alkyl esters and the hydrolysis of the sulfonated phosphoric acid esters formed.
2. Discussion of Related Art:
While the use of phosphates and phosphonates as builders in detergent compositions is widespread, phosphoric compounds have previously been used as surfactants only to a lesser degree.
The synthesis of surfactants containing phosphorus by the reaction of saturated .alpha.-bromo-fatty acid esters with triethylphosphite has been described more than 20 years ago by Maurer et al. in J. Am. Oil Chem. Soc. 41, 205 (1964). However the o-phosphono-fatty acid esters only have average surface-active properties. Recently, the manufacture of alkyl phosphinates by the reaction of alpha-olefins with phosphorous or hypophosphorous acids has been disclosed (C. Herranz in J. Am. Oil Chem. Soc. 64, 1038 (1987). These substances also only have moderate washing and foaming properties.
Compared with the surfactants described by Maurer and Herranz, in which phosphorus is directly linked with a carbon chain, phosphoric acid esters with P-O-C-bonds have clearly improved surfactant properties. It is, for example, known that alkyl phosphates can be used as wetting agents, antistatic agents, emulsifying agents and in detergents and cleaning agents (A. J. Olenick, W. C. Smith in Soap, Cosm. Chem. Spec. 7, 26 (1986)). However these substances have only a slight foaming capacity, they are less resistant to hard water, and some are poorly soluble in water.
From Acta Polym. 38, 5 (1987) the use of alkyl phosphates, manufactured by the reaction of alcohols or alcohol polyoxy alkyl ethers with POCl.sub.3 as antistatic agents for synthetic fibers is also known.
An object of this invention is to improve the surface-active properties, the water solubility, and particularly the resistance to hard water of long-chain alkyl phosphates.